This invention relates to a hinge mount for seats having an adjustable seat back, particularly for motor vehicle seats, in which a stationary hinge member assigned to the seat proper and a tiltable hinge member assigned to the seat back are coupled one to another by means of a rotary axle whereby a wobble gear assembly for adjusting the angular position of the two hinge members is constituted of a spur gear integrally formed on one of the hinge members and of an internal gear integrally formed on the other hinge member, the spur gear being of smaller diameter than the inner diameter of the internal gear to engage the latter at one point. A rotary axle having a concentric portion supported for rotation at the center of one gear and an eccentric portion supported for rotation at the center of the other gear controls the engagement and disengagement of the two gears during the position adjustment of the seat back. Both the internal gear and the spur gear are impressed in the wall of the assigned hinge member and are connected thereby by wall bridges.
In a known hinge mount of the above-described type the impressed portions of the hinge members forming the gears project above the corresponding surface of the hinge member only to such an extent that the wall of the impressed gear partially overlaps the thickness of the wall of the assigned hinge member whereby in the range of the formation between the hinge member and its impressed portion forms the bridge wall connecting the peripheral region of the impressed gear to the hinge member. In such prior-art hinge mounts, however, the inner surface of the impressed portion is not in alignment with the outer surface of the hinge member. It is true that the impressed gear and the remaining hinge member have the same wall thickness which for the sake of strength is determined by the desired width of teeth of the gears and the necessary strength of the wall bridge remaining between the inner teeth in the wall of the hinge member and the external teeth in the wall of the corresponding impressed portion. By means of a finishing stamping process it is possible to produce on the hinge members both external teeth and depending on the finishing stamping process also internal teeth corresponding in size and in number to one another. In the wobble gear assembly, however, each hinge member uses either the internal teeth or the external teeth only whereas the other teeth which result from the employed manufacturing process remain unused. Due to the existence of the overlapping wall portion between the two gears on each hinge member the thickness of the wall of the latter results larger than it would be necessary for the transmission of the supporting forces.